Well yea...you can 'toss' any fish and any plant in there - BUT .....Chances are you'll be back here posting real quick something along the lines of "plants turning yellow, fish dieing, fish has hole etc etc"
To avoid these headaches, easiest thing is: Test your water for pH & KH, whatever the result, there'll be a nice range of fish you can house in this water - See what you like from them, that then won't be followed by upset posts Same on the plants, some need more light (> more nutrition) other don't.

You can house shrimp either in community tanks or (like me) in sperated small tanks. Their behavior is too awesome to watch and too funny at times. Ideally for them to stand out best way possible, you want a heavily planted tank with dark substrate for them to live in. Apart from my profile, here's more shrimpy pic's http://www.tropicalfishkeeping.com/f...ictures-34455/

Like I said before, KH & Ph unless you already have your eyes set on ONE specific fish - Whatever the result will be you'll have plenty fish options. For NO2, NO3, Ammonia - At first while cycling you will see these numbers rise & fall, thereafter the goal is to keep them 0 - If that's not the case, something is wrong in the tank (often due to too lil water exchanges)

If you want Discus again, go for it! Maybe 2 of them, a nice school of Tetra's and a school of 10-20 Cory on the bottom - Provided you have soft acidic water to support this idea

~ Life Is Too Short, Break The Rules, Forgive Quickly, Kiss Slowly, Love Truly, Laugh Uncontrollably And Never Regret Anything that Made You Smile.
Life May Not Be The Party We Hoped For, But While We're Here, We Should Dance. ~

They're indeed VERY pretty one's and don't get too large neither. When I had them in my farm, I came to learn that when fed dried pumpkin slices, that REALLY enhances their red coloration.
They just absolutely do NOT do well in newly set up systems, so I'd strongly suggest to have your tank planted and stock with fish for several months min before adding these guys.

~ Life Is Too Short, Break The Rules, Forgive Quickly, Kiss Slowly, Love Truly, Laugh Uncontrollably And Never Regret Anything that Made You Smile.
Life May Not Be The Party We Hoped For, But While We're Here, We Should Dance. ~